The testes are internal male reproductive organs. A normal male has two testes, located on the left and right side of the scrotum. The testicles are oval in shape and gray in color. In adults, the testicles are 3.5-4.5 cm long, 2-3 cm wide and 1-2 cm thick, and each side weighs 10-15 grams. The left side is usually about 1 cm lower than the right side. Some people have a large testicle and a small testicle, one high and one low, if the difference is not big, are normal. There are two main congenital causes. One is congenital testicular dysplasia, which is caused by chromosomal abnormalities and occurs in about one in 400 male infants. This kind of patients mostly see delayed puberty development, male secondary sexual characteristics are not obvious, and 80% of patients can show feminization such as breast enlargement. The treatment of this disease is mainly to supplement androgens to restore the male physique and maintain the sexual function of the patient. Another type of congenital adrenal hyperplasia is the large increase of androgens synthesized in the adrenal glands, which inhibits the secretion of gonadotropins by the pituitary gland, which in turn inhibits testicular development. In this case, the patient shows precocious puberty, with male secondary sexual characteristics appearing before the age of 10, but the testes are still small. This disease is treated with cortisone abroad to lower the plasma androgens, thus allowing the testes to develop. So, how can patients with tiny testicles be prevented? The following are the preventive measures for tiny testicles: 1, to choose healthy and comfortable underwear. 2, reasonable diet, moderate exercise, quit smoking and limit alcohol, and develop good hygiene and rest habits.